The effect of arm muscle discrete relaxation training and fine-coordination training on proprioceptive control

Proprioception makes an important contribution to the regulation of speed, strength and spatial parameters of movements, determining the level of proficiency in motor skills. However, the effectiveness of various training approaches in relation to voluntary proprioceptive control of target muscles has not been sufficiently studied. In this paper, we investigated the effectiveness of three types of manipulative training: 1) fine coordination, 2) discrete muscle relaxation and 3) their combinations in relation to the accuracy of reproducing: а) the angular deviation of the joystick from the vertical and b) static muscle efforts during the pronation and supination of the joystick. The study involved 40 young (18-35 years old), physically active volunteers who randomly made up 4 groups of 10 people: “Control” (lack of training), “Coordination” (training of passing an analog of a slit maze with a thin probe), “Discrete relaxation” (training of discrete muscle relaxation of pronators and supinators of the forearm), “Combined” (combined training of maze passing and discrete relaxation). Before and after training (n = 10) we evaluated: 1) the accuracy of reproduction of the deviation of the wrist joystick from the vertical by 20, 50, 80 degrees and 2) the accuracy of reproduction of isometric contraction (0, 20, 50 and 80% of the maximum effort) in the descending, ascending directions as well as discrete achievement of any effort level by pronation /supination of the wrist joystick. It was found that coordination training increased the length of the traversed path in 3 minutes with a reduced number of errors, and increased the proprioceptive accuracy of reproducing the angle of deviation of the joystick by 20 degrees also. In the “Discrete Relaxation” group the average modulus of errors in reproducing descending, ascending and discrete forces during supination, as well as the average modulus of errors in reproducing descending, ascending and discrete forces during forearm pronation decreased after course training. At the same time, no changes in the accuracy of reproducing the angular positions of the joystick were found in this group. In the “Combined” group, training led to an increase in the accuracy of reproducing ascending and descending efforts during pronation, as well as the accuracy of descending efforts during supination of the forearm. In addition, in this group, a decrease in the error modulus during reproducing the tilt of the joystick by 50 degrees by supination was revealed. Correlation analysis did not reveal positive links between training changes in proprioceptive control of different modality. Thus, the training effects used on the target muscles of the forearm have a specific effect on the proprioceptive control of muscle effort and spatial position in the hand joints. The high efficiency of discrete relaxation training regarding the accuracy of voluntary efforts allows us to recommend its use in order to increase the level of mastery of the motor skills of the hand.